The present invention relates generally to the field of spray devices, such as spray guns for pressure washers and sprayers for garden hoses. More specifically the present invention relates to a system for controllably injecting a chemical, such as soap, solvent, pesticide, or fertilizer, into a water stream that is ejected from a spray gun, sprayer, or spray nozzle.
Spray devices, such as pressure washer spray guns, are used for cleaning, stripping, watering, and other functions. Some spray devices include systems for injecting soap and other chemicals into the spray stream, such as devices employing a soaper nozzle (also called a soap nozzle). A user attaches the soaper nozzle to a spray gun, and when the spray device is activated, soap is incorporated into the water flow via a venturi located on a typical pressure washer pump. The rate of soap injected into the water flow is a function of water flow rate and pressure in the soaper nozzle and design of the venturi.